Electrophotographic material

ABSTRACT

AN IMPROVED ELECTROPHOTOGRAPHIC MATERIAL COMPRISING A CONDUCTIVE SUPPORT LAYER AND A PHOTOCONDUCTIVE INSULATING LAYER, THE LATTER COMPRISING A COMBINATION OF A PHOTOCONDUCTIVE POLY-COMPOUND AND A CARBONIUM SALT AS NOVEL SENSITIZER, SAID PHOTOCONDUCTIVE POLYMERIC COMPOUND COMPRISING AT LEAST ONE OF POLY-N-VINYLCARBAZOLE, POLY-3,6DIBROMO-N-VINYLCARBAZOLE, BROMINATED POLY-N-VINYLCARBAZOLE, POLYACENAPHTHLENE AND POLYVINYLANTHRACENE.

April 20, i971 YosHmoBu Mummw ETAL l ,75,6%

v y *l l ELECTROPHOTOGRAPHIC MATERIAL y med June rr, 196sy "s sxwwwnm z I 300 40o svn mo 'im/w Fig 5 Po ly-N-vinylcazbazole I 40o .$720 60o 700 4,1/4.

Fig. 6 Poly-N-vinylcarbaza1e+compound 3 Fig. 7 Poly-N-vinylcarbazole+compound l1 .30o s200 .90o ao lu YOSHNDBU nwo KAZ U H lSA MOPJMTO. muemnns April 20 1971v YosHlNoBu MURAKAM Erm. 3,575,698

y `ELEcTRoPHoTOGRAJPHIcMATERIAL med June 1v, 196s v f s Shana-snm #no .$00 ou 700 my.

Fig. 9 Poly-3,-dibromo-N-vinylcarbazo1e+compound 114 40o v $00 600 7m la Fivg. l0 Poly-3,6dibromo-N-vinylcarbazole+compound 16 l l l Fig. 11 Bromixgated poly-N-iriny1carbazo1e+ompoud ll,

Yosmmau Mmmm w KAZLHISA NDRIMDTD.mven1-nac l wmmmmlmm MW United States Patent Oii U.S. Cl. 96-1.6 5 Claims ABSTRACT F THE DISCLOSURE An improved electrophotographic material comprising a conductive support layer and a photoconductive insulating layer, the latter comprising a combination of a photoconductive poly-compound and a carbonium salt as novel sensitizer, said photoconductive polymeric compound comprising at least one of poly-N-vinylcarbazole, poly-3,6- dibromo-N-vinylcarbazole, brominated poly-N-vinylcarbazole, polyacenaphthylene and polyvinylanthracene.

This invention relates to novel light-sensitive layers and more particularly to electrophotographic light-sensitive polymer layers containing a carbonium salt as a novel sensitizer of organic photoconductors.

Various light-sensitive layers are well known inl the electrophotographic art for making copies of documents, drawings, transparencies, etc. 'Ihese layers contain an organic photoconductive compound, such as poly-N-vinylcarbazole, poly-3,6-dibromo-N-vinylcarbazole, brominated poly-N-vinylcarbazole, polyacenaphthylene, polyvinylanthracene, etc. These layers are non-conductors of electricity before exposure and become electrical conductors upon exposure.

It is necessary for the electrophotographic art that the photoconductive material has a high photoconductivity in the long wavelength region of the Visible spectrum. Such a photoconductive material makes it possible for the electrophotographic art to employ inexpensive and convenient light sources such as incandescent lamps inl a reduced eX- posure time and to reproduce colored pictures. The photoconductive materials mentioned above, however, have usually a low photoconductivity and spectrum characteristics sensitive to the short wavelength region of the exposure light and do not satisfy entirely the above requirement.

It is known that an addition of a so-called sensitizer can improve photoconductivity and spectrum characteristics of the above photoconductive compounds. Conventional sensitizers are dyestuff compounds, such as triarylmethan'e dyes, xanthene dyes, triazine dyes or acridine dyes, but the conventional sensitizers are not entirely satisfactory for improving the photoconductivity and the spectrum characteristics of the available photoconductive compounds.

In addition to the high photoconductivity and spectrum characteristics sensitive to visible light, the electrophotographic art requires a high electric resistance of photoconductive materials in the dark. Conventional sensitizers are apt to increase the dark conductivity whereas they promote the photoconductivity. A high dark conductivity of photoconductive materials is not desirable because it results in a loss of the applied electrostatic charge in the dark.

Anl objec-t of the invention is to provide electrophotographic materials having a high photoconductivity and spectrum characteristics sensitive to a long wavelength region of the visible spectrum.

Another object of the invention is to provide electro- 3,575,698 Patented Apr. 20, 1971 ICC photographic materials having a high electric resistance in the dark.

These and other objects are accomplished by adding a carbonium salt as a sensitizer to poly-N-vinylcarbazole, poly-3,6-dibromo-N-vinylcarbazole, brominated poly-N- vinylcarbazole, polyacenaphthylene or polyvinylanthracene, as a light-senesitive film-forming composition.

The invention is further explained in the following description with reference to the accompanying drawings wherein:

FIG. l represents the wedge spectrogram for an electrophotographic material coated with an unsensitized solution of 10 weight percent of brominated poly-N-Vinylcarbazole irny chlorobenzene.

FIG. 2 represents the wedge spectrogram for an electrophotographic material coated with a solution containing l0 weight percent of brominated poly-N-vinylcarbazole, and, as a sensitizer, 0.04 weight percent of tris(4- methoxyphenyl)carbonium perchlorate, said brominated poly-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 3 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of brominated poly-N-vinylcarbazole, and, as a sensitizer, 0.04 weight percent of bis(4methoxy phenyD-Z methoxynaphthyl(l)carbonium perchlorate, said brominated poly-N-vinylcarbazole being dissolved in a solvent of four Weight parts of chlorobenzene and one lweight part of dichloroethane.

FIG. 4 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 Weight percent of brominated poly-N-vinylcarbazole, and, as a sensitizer, 0.04 Weight percent of bis (4-methoxyphenyl)-w-phenylbutadienylcarbonium percholrate, said brominlated poly-N-vinylcarbazole being dissolved in a solvent of four Weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 5 represents the wedge spectrogram for an electrophotographic material coated with an unsensitized solution of 10 weight percent of poly-N-vinlycarbazole in chloroben'zene.

FIG. 6 represents the Wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of poly-N-vinylcarbazole, and, as a sensitizer, 0.04 weight percent of bis(4methoxyphenyl) naphthyl(l)carboniurn perchlorate, said poly-N-vinylcarbazole beinlg dissolved in a solvent of four Weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 7 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of poly-N-Vinylcarbazole, and, as a sensitizer, 0.04 weight percent of phenyl(4methoxyphen yl)-4-methoxynaphthyl(1')carbonium perchlorate, said poly-N-vinylcarbazole being dissolved in a solvent of four Weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 8 represents the wedge spectrogram for an electrophotographic material coated with an unsensitized solution of 10 weight percent of poly-3,-dibromo-N-vinylcarbazole in chlorobenzene.

FIG. 9 represents the wedge spectrogram for an electrophotographic material coated with a solution containing l0 weight percent of poly-3,6-dibromo-N-vinylcarbazole, and, as a sensitizer, 0.04 weight percent of phenyl(4 methoxyphenyl) 2' methoxynaphthyl( l)carbonium perchlorate, said poly-3,6-dibromo-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. l0 represents the wedge spectrogram for an electrophotographic material coated with a solution containing weight percent of poly-3,-dibronio-N-vinylcarbazole, and, as a sensitizer, 0.04 weight percent of bis(4 methoxyphenyl phenanthryl 9 carbonium perchlorate, said poly-3,6-dibromo-N-vinylcarbazole being dissolved in a solvent of four Weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 11 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of brominated poly-N-vinylcarbazole, and, as sensitizers, 0.024 weight percent of phenyl- (4-methoxyphenyl) 4 methoxynaphthyl(1)carboniurn perchlorate, 0.012 weight percent of bis(4methoxyphenyl) 2 methoxynaphthyl( l)carbonium perchlorate and 0.024 weight percent of phenyl(4-methoxyphenyl)2' methoxynaphthyl(1')carbonium perchlorate, said brominated poly-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one weight part of dichloroethane.

The carbonium salt compound (sensitizer) according t0 the present invention has the following formula:

Ri 'l' i l Arnon- C Re R3 wherein R1, R2, R3 each is an aliphatic group such as styryl, 2-methoxystyryl, 4-methoxystyryl or w-phenylbutadienyl, phenyl or 4-biphenyl, alkoxyphenyl such as Z-methoxyphenyl, 4methoxyphenyl, 4-ethoxyphenyl, 3,4-dimethoxyphenyl or 3,4-diethoXyphenyl, plienoxyphenyl, naphthyl, alkoxynaphthyl such as 2-methoxynaphthyl, 4-methoxynaphthyl, Z-ethOXynaphtliyl or 4-ethoxynaphthyl, anthryl, alkoxyanthryl, phenanthryl or alkoxyphenanthryl.

Anion is anionic function selected from the group consisting of uoborate, chloride, iodide, perchlorate, chloroferrate and chlorozincate.

The carbonium salts are prepared generally by one of two methods. A rst method is based on the reaction of a Grignard reagent (I) in ether or in a mixed solvent of ether and benzene with a ketone compound (II). After the reaction product is hydrolyzed with an aqueous solution of ammonium chloride, the product (III) is treated with perchloric acid to obtain perchlorate (IV) in the presence of acetic acid and acetic anhydride. This reaction is shown by the following chemical equation:

A second method is achieved by the reaction of carbinol intermediate (V) containing a methylene group, with an aromatic aldehyde (VI) in the presence of perchloric acid and hydrogen chloride. This reaction product (VII) is characterized by an ethenyl linkage. This reaction is shown by the following chemical equation:

(VII) Representative examples of the carbonium salts according to the invention are listed in Table l.

TABLE 1 Compound Number Name of compound Bis(4-metlioxyplienyl)styrylcarbonium perchlorate. Tris(4-metlioxyphenyl)carbonium perchlorate. Bis4-mcthoxyplienyl)naphtl1yl(1)carbonium perchlora e. Tris (4-metlioxyplienyl) carbonium chleroerrate.

Diplienyl-naphthyl(Dcarboniuin perchlorate.

Plienyl(4-etlioxynaphthyl(1))earboninm perchlorate. Phenyl(4-metlioxynaplithyl(1))naphthyl(1)carboninm perchlorate. Phenyl-hiphenyl(4)naphthyl(1)earboiiium perchlorate. llieriyl-bis(4-methoxyphenyl)carboiiiuni clilorolcrratc. Phcnyl(3,4-dimethoxyphcnyl)biphciiyl(4)carboniuin perchlorate. llieny1(4-inothoxypl1cnyl) J1ii1etlioxynaphtliyl(1 carboniuin perchlorate.

12 Phenyl-bis(4-eth0xyphcnyl)earbonium perchlorate.

14 Pheiiyl(4methcxyphenyl)-2niethoxynapl1thyl(l)- cai-bc nium perchlorate.

15.-... Plienyl-biphenyl (4) (2methoxynaphthyl(1)) carbonlum perchlorate. l

16 Bis(4-metlioxyplienyl)phenanthryl(9)carbonium perchlorate.

17 Phenyl(3,4-dietlioxyphenyDphenanthryl(l/)carbonium perchlorate. l

18 Plienyl(4methoxynaphthyl(1))phenanthryl(9)carbon1 um cliloroferrate.

19 Bis (4-metlioxyphenyl) 4phenoxyphenylcarbornum iluoborate.

20 Phenyl(4etlioxyphenyl)-4phenoxyphenylcarbouium perchlorate.

21 Phenyl(4-phcnoxyphenyl)-4metlioxynaphthyl(1')- carboninm perchlorate.

22 BisolbmethoxyphcnyDA'-methoxystyrylcarboniuni perc i orate.

23 Bis (4- ietlioxyphenyl) lii-phenylbutadicnylcarbonium perchlorate.

24 Bis(4mctl1oxyphenyl)-a-(4inethoxyplienyl)4"- mcthoxystyrylcarhoniiiin perchlorate.

25 Bis(4-methoxyphcnyl)-a-(4/-methoxyphenyD-wplienylbutadienylcarbonium perchlorate.

26 Plienyl-his(4methoxypheiiyl)carboniuni perchlorate.

27 Dipheiiyl(4-inethoxyphenyl)carboniuni perchlorate.

28 'lriplienylearhoninm perchlorate. l

29 Phenyl(4-niethoxyphenyl)naplithyl(1')carb0nium perchlorate.

80 Plienyl(4-nietlioxyplienyl) biphenyl(4)carbon1uiu perchlorate.

31 Phenyl(4-metlioxyphenyl)phenaiithryl(9)carhonluni perchlorate.

32 Phenyl (4-metlioxynaphtliyl (1) plienanthryl (9') carbonium perchlorate. l

33 Phenyl-biphenyl(4)plienanthryl(9')earbonlum perchlorate.

34 Bis(4methoxyphenyl)4plicnoxyphenylcarbonium perchlorate.

35 Phenyl(4-methoxyphcnyl)-4phenoxyphcnylcarhoniunl perchlorate. l

36. llilerliyl-biplienylti) -4/-plienoxyphenylcarhoinuni pere i orate.

37 Tris(4-methoxyphenyl)earboniuin iodide.

38.. Tris(4-methoxyphenyl)carbonium ehlorozincate.

r. 30.. Tris(4methoxyphenyl)carbonium iluoroborate. 40 40 Tris(4-methoxyphenyl)carbonum chloride.

Table 2 lists additional information on the color in dichloroethane and melting point of the novel compounds according to the invention.

TABLE 2 Melting Compound point Number Color in dichloroethane C.)

1 Reddisli violet 93-95 2- Reddisli orange 192-163 3. Reddish violet 1 162 4- Reddish orange 168-169 5- Brown 1 287 7. Rcddish orange 1 241 8. Violet 300 9. Reddish orange 131-132 11 Greenish blue l 135 13 Rcddish violet 1 162 14 Grcenlsh yellow 1 141 15 R d 300 16 139-143 21 Grecnisli blue 121-123 22 Reddish violet 135-137 23 Violet 158-161 24 Reddsh orange. 300 gg R 2 1 282 10-212 27 194-195 28. 154-157 29 123-126 30. 132-134 31 12T-130 3-. Reddish orange. 247-249 33.- Reddish violet 1 262 34 Reddish orange 108-112 35.. do -88 36. Red 98-102 37.. Reddisli orange 148-149 38.. do 234-235 39.... dO... 18S-190 40 do 147-148 1 Deconipose.

A simple per se well known exchange reaction makes it possible for the anionic function of the carbonium salt compounds to consist of \Cl, I, B134-, ZnCl3, FeCl4 or C1041 The following description will explain a practical method for making carbonium salts with reference to exemplary compounds. The details of the preparation of other compounds will be apparent to the skilled in the art from the preceding disclosure and the following illustrative examples of preparation methods of various compounds according to the invention:

(a) Bis(4methoxyphenyl)styrylcarbonium perchlorate (compound No. 1)

I ClOt" /C\ To a Grignard reagent prepared from 18 grams of -bromostyrene, 2.4 grams of magnesium and a small amount of iodine in 50 milliliters of dry ether, there are slowly added 5 grams of p,p'-dimethoxybenzophenone. The solution is then refluxed for 2 hours and poured into an aqueous solution of ammonium chloride to hydrolyze the reaction product. The ether solution of the product is dried with anhydrous sodium sulfate. The solution is filtered and diluted with ether to 300 milliliters. To the solution, there are added milliliters of acetic acid and 10 milliliters of acetic anhydride, then the solution is cooled and treated slowly with 6 milliliters of 60% perchloric acid. Precipitated crystals are filtered otf, washed with ether and dried to obtain 4.3 grams of red crystals having a melting point of 93 to 95 C.

CHsO- (VIII) (b) Tris(4methoxyphenyl)carbonium perchlorate (compound No, 2) and chloroferrate (compound No. 4)

CHaO- -OCHa To a Grignard reagent prepared from 2.8 grams of p-bromoanisole, 0.36 gram of magnesium and a small amount of iodine in 10 milliliters of dry ether, there are slowly added 2.5 grams of p,p'-dirnethoxybenzophenone. The solution is then relluxed for 1 hour and poured into an aqueous `solution of ammonium chloride to hydrolyze the reaction product. The ether solution of the product is dried with anhydrous sodium sulfate. The solution is ltered and diluted with ether to 300 milliliters.l To the solution, there are added 10 milliliters of acetic acid and 10 milliliters of acetic anhydride, and then the solution is cooled and treated slowly with 3 milliliters of 60% perchloric acid. Precipitated crystals are collected, washed with ether and recrystallized twice from acetic acid to obtain 2.3 grams of reddish orange crystals of perchlorate which have a melting point of 192 to 193 C.

Furthermore, 1 gram of the crystals is dissolved in 30 milliliters of concentrated hydrochloric acid, and successively, 20 milliliters of acetic acid. To the solution are added 30 milliliters of concentrated hydrochloric acid containing 5 grams of ferrie chloride, then precipitated crystals vare collected and recrystallized from acetic acid to obtain 0.9 gram of chloroferrate crystals having a melting point of 168 C. to 169 C.

(c) Phenyl bis(4 methoxyphenyl)carbonium perchlorate (compound No. 26) and chloroferrate (compound CHaO- 00H3 To a Grignard reagent prepared from 4.7 grams of p-bromoanisole, 0.6 gram of magnesium and a small amount of iodine in 15 milliliters of dry ether, there are slowly added 3.4 grams of p-methoxybenzophenone. After the solution is then reuxed for l hour, the solution is hydrolyzed by being poured into an aqueous solution of ammonium chloride. The ether solution is dried with anhydrous sodium sulfate, after which milliliters of ether are added to the solution, followed by 10 milliliters of acetic acid and l0 milliliters of acetic anhydride; then the solution is cooled and treated slowly with 3 milliliters of 60% perchloric acid. Precipitated crystals are collected, Washed with ether and recrystallized from a mixed solvent of acetic acid and dichloroethane (5 :'1). The crystals of perchlorate thus obtained have a melting point of 210 to 212 C.

lFurthermore, 0.5 gram of the crystals is dissolved in 15 milliliters of concentrated hydrochloric acid and, successively, 15 milliliters of acetic acid. To the solution, then are added 2.5 grams of ferric chloride dissolved in 15 milliliters of concentrated hydrochloric acid. The precipitated crystals are collected and recrystallized from acetic acid. The amount of the crystals is 0.4 gram. The needle-like crystals of chloroferrate obtained have a melting point of 131 to 132 C.

(d) Bis (4-methoxyphenyl) -2methoxynaphthyl( 1') carbonium perchlorate (compound No. 13)

COHS I I C104 C HaCO- To a Grignard reagent prepared from 6 grams of w bromo--methoxynaphthalene, 0.6 gram of magnesium and a small amount of iodine in 20 milliliters of dry ether and 10 milliliters of dry benzene, there are slowly added 3.8 grams of p,p'-dimethoxybenzophenone. After the solution is then reuxed for 1 hour, the solution is poured into an aqueous solution of ammonium chloride. The ether solution is dried with anhydrous sodium sulfate and then 100 milliliters of ether are added to the solution followed by 10 milliliters of acetic acid and, successively, 10 milliliters of acetic anhydride; then the solution is treated slowly with 3 milliliters of 60% perchloric acid. Precipitated crystals are collected and reprecipitated again by pouring the dichloro ethane solution into ether. The crystals of perchlorate thus obtained have a decom- (e) Phenyl 4phenoxyphenyl) 4methoxynaphthyl (l)carbonium perchlorate (compound No. 21)

@-i-Q-O-Q To a Grignard reagent prepared from 6.2 grams of pbromo-diphenylether, 0.6 gram of magnesium and a small amount of iodine in 2O milliliters of dry ether, there are slowly added 4.2 grams of 1benzoyl-4-methoxynaphthalene in 20 milliliters of dry ether. After the solution is then refluxed for 1 hour, the solution is hydrolyzed by being poured into an aqueous solution of ammonium chloride. The ether solution is dried with anhydrous sodium sulfate, after which 100 milliliters of ether are added to the solution. To the latter, there are then added milliliters of acetic acid and l0 milliliters of acetic anhydride, and then the solution is treated slowly with 3 milliliters of 60% perchloric acid. Precipitated crystals are collected and reprecipitated from the dichloroethane solution by means of ether. The crystals of perchlorate thus obtained have a melting point of 121 to 123 C. The amount of the crystals is 1.5 grams.

(f) Bis( 4-methoxyphenyl)-w-phenylbutadienylcarbonium perchlorate (compound No. 23)

O C H3 i' CIIaO- To a Grignard reagent prepared from 9.4 grams of pbromoanisole, 1.2 grams of magnesium and a small amount of iodine in 30 milliliters of dry ether, there are slowly added 4.8 grams of p-methoxyacetophenone in milliliters of dry ether. After the solution is then reuxed for 1 hour, the solution is poured into an aqueous solution of ammonium chloride. The ether solution is dried with anhydrous sodium sulfate, and to the solution there are added 100 milliliters of ether, followed by 3.9 grams of cinnamaldehyde and 4 milliliters of 70% perchlorio acid, and then, after the solution is cooled, it is saturated with dry hydrogen chloride gas. After standing in an ice-box, the solution is slowly diluted with 500 milliliters of ether and the precipitated crystals are collected and washed with ether thoroughly. The crystals are dissolved in dichloroethane and poured into ether to purify the same. The amount of purified crystals is 1.5 grams and they have a melting point of 158 to 161 C.

It has been discovered according to the invention that the compounds listed in Table l are sensitizing agents which can improve the photoconductivity and the spectrum characteristics of photoconductive polymers such as poly-N-vinylcarbazole, poly-3,6-dibromo-N-vinylcarbazole, brominated poly-N-vinylcarbazole, polyacenaphthylene and polyvinylanthracene. These polymers, except brominated poly-N-vinylcarbazole, are prepared in a per se well known method. The brominated poly-N-vinylcarbazole can be prepared by the following method: To the solution of 20 grams of poly-N-vinylcarbazole in 450 milliliters of chlorobenzene, there are added 18.44 grams of N-bromosuccinimide and 0.173 gram of benzoyl peroxide. The mixture is heated at 80 C. for 2 hours while being stirred thoroughly and is poured into methanol to obtain a white polymer. The white polymer is dissolved in chlorobenzene and again poured into methanol for purification. The pure polymer thus obtained as a precipitate exhibits upon elementary analysis a halogen content of 29.87 weight percent which approximates the value calculated, i.e. 29.44 weight percent of the monobromosubstituted product from poly-N-vinylcarbazole. This indicates that the polymer obtained is a monobromosubstituted product. The degree of brominatiaon varies from 50 mole percent to 200 mole percent according to reaction conditions.

The novel sensitizer comprising at least one compound from the group listed in Table 1 is dissolved in a suitable solvent, such as methanol, dichloroethane, methylene chloride, chloroform, or a `combination thereof, and is added to the solution of the photoconductive polymer described above. The amount of the sensitizer added is from 0.01 to 3.0 weight parts in connection with weight parts of the photoconductive polymer. Advantageously, the amount thereof is from 0.1 to 2.0 weight parts in connection with 100 weight parts of the photoconductive polymer.

The novel sensitizers according to the present invention differ from the well-known triphenylmethane dye-stuffs in the following two points:

First, the triphenylmethane dyestuffs have at least two radicals selected from the radical group comprising the amino, monomethylamino and dimethylamino radicals. The novel sensitizers according to the invention do not have such a radical.

Secondly, the novel sensitizers have an extreme ability to increase the photosensitivity of said organic photoconductors. F or example, when the novel sensitizer, compound No. 2 (XIV), is used as a sensitizer 0f poly-N-vinylcarbazole, the photosensitive layer has a ten times higher sensitivity than the layer of poly-N-vinylcarbazole sensitized with a derivative (XV) of crystal violet which is a representative example of the triphenylmethane dyestuffs:

OCHi

IUCHaM (XIV) By suitable combinations of the novel sensitizers mentioned above, highly sensitive and panchromatic photosensitive layers are, obtained easily.

For the preparation of rthe photoconductive insulating layer, a said solution of the photoconductive polymer and the carbonium salt in a suitable solvent is applied to the electroconductive support in per se usual manner, for example, by spraying lby direct application, by means of blade coating, by means of whirler coating, etc., and rthen dried so as to produce a homogeneous photoconductive insulating layer on the electroconductive suppOrt. Operable solvents are benzene, toluene, chlorobenzene, dioxane, methylene chloride, dichloroethane and combinations thereof. Said solution may be incorporated with suitable plasticizers and/or organic colloids for improving the flexibility and strength of the photoconductive polymer. Operable plasticizers are as follows: chlorinated diphenyl, dimethyl phthalate, `diethyl phthalate and octyl phthalate. Operable organic colloids are as follows: natural and synthetic resins, e.g. phenol resin, phenol resin modified with rosin, polyvinyl acetal, polyvinyl butyral, polyvinyl cinnamate, polycarbonate resin. `Operable materials for electrooonductive supports may -be made of any materials which satisfy the requirement of the electrophotographic art, e.g. metal plate or glass plate having NESA coating,

`plate or foils made of electrically conductive resins or coated with evaporated thin metal layer. If paper is to be used as a support for the photoconductive layer, pretreatment of the paper against penetration of the coating solution is advisable. The transparent support can produce a transparent electrophotographic plate, foil or lm. After 'an electrostatic charge has been applied, i.e., after the layer has been charged positively or negatively by means of a corona discharge, the layer becomeslight sensitive.

The reproduction of images by the eleetrophotographic method is carried out as follows: when the photoconductive -layer has been charged by means of a corona discharge apparatus, the support with the sensitized layer is exposed to light under a master and is then dusted over in a per se known manner with a resin powder colored with carbon black. The image that now becomes visible can easily be wiped off. It can also be fixed by heating at about 120 C. From positive masters, positive images characterized by good contrast are produced.

It has been discovered according to the invention that more advantageous electrophotographic material can be prepared by a combination of brominated poly-N-vinylcarbazole and, as ycarbonium salt, at least one of the following compounds:

bis (Li-methoxyphenyl styrylcarbonium perchlorate,

bis (4-methoxyphenyl) naphthyl( 1 carbonium phenyl (4-methoxyphenyl) 4methoxynaphthy1( 1') carbonium perchlorate,

bis (4-meth0xyphenyl) -2methoxynaphthyl( 1 )carbonium perchlorate,

phenyl( 4methoxyphenyl) 2'methoxynaphthyl( 1') carbonium perchlorate,

bis(4methoxyphenyl) phenanthryl (9 carbonium perchlorate,

phenyl (4-phenoxyphenyl) -4methoxynaphthyl( 1 carbonium perchlorate,

bis (4methoxypheny1) -4m'ethoxystyrylcarbonium perchlorate,

bis (4-methoxyphenyl) w-phenylbutadienylcarbonium perchlorate,

bis (4-methoxyphenyl) -a- (4methoxyphenyl 4 methoxystyrylcarbonium perchlorate,

phenylbis (4-methoxyphenyl) carb onium perchlorate,

and combinations thereof.

This invention is still further illustrated with reference to the following illustrative examples.

EXAMPLE 1 1 gram of polyacenaphthylene and 0.6 gram of, as a plasticizer, chlorinated diphenyl (commercially available as Kanechlor), are dissolved in 15 milliliters of dichloroethane. To the solution are added 0.5 milliliterof dichloroethane containing 0.005 gram of a carbonium salt corresponding to compound number 2, 3, 9, 11, 13, 14, 21 or 22 of Table 1. The solution is applied to an aluminum plate by means of whirler coating and is dried to form a layer of 3p. in thickness After said aluminum plate provided with the layer is charged negatively by means of corona discharge with a charging device maintained at approximately 6000 volts in the dark, it is placed under a positive master and is exposed to a 100 w. tungsten lamp at an illumination of 50 luxes, and the said plate is powdered over with a developer in a per se known manner This developer consists of toner and carrier The toner consists of a low melting point polystyrene, colophony Aand carbon black The toner is mixed with a carrier 10 substance such that the toner becomes triboelectrically charged with a charge opposite to that produced on the plate. A positive image is produced and is fixed by slight heating. In Table 3, there are shown the optimum amounts o'f exposure in lux-second units.

TABLE 3 Optimum exposure Compound number: (lux-sec.) No sensitizer 200,000 2 420 3 84 9 860 11 92 13 78 14 84 21 92 22 81 EXAMPLE 2 1 gram of poly-N-vinylcarbazole and 0.004 gram of a carbonium salt corresponding to compound number 2, 3, 6, 9, 11, 1.2, 13, =14, 16, 17, 19, 21, 22, 23, 24 or 25 of Table 1 are dissolved in 10 milliliters of dichloroethane.

The solution is applied to an aluminum plate and is dried to form a layer of 10a in thickness. An electrophotographic image is produced in the same Way as that described in Example 1. In Table 4, there are shown the optimum amounts of exposure in lux-second units to produce exactly the original images.

It is clear from Table 4 and FIGS. 5 to 7 that the novel sensitizers improve the photoconductivity and the characteristics of poly-N-'vinylcarbazo1e.

EXAMPLE 3 l gram of poly-3,6-dibromo-N-Ninylcarbazole, 0.5 gram of chlorinated diphenyl (commercially available as Kanechlor) and 0.004 gram of a carbonium salt corresponding to compound number 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1f1, 12, 13, 14, 15, 16, 17, 18, 19, 20, 2l, 22, 23, 24, 25, or 26 of Table 1 are dissolved in 10 milliliters of dichloroethane. This solution is applied to an aluminum plate by means of a blade coating and dried to form a layer of 14n in thickness. On these supports, electrophotographic images are produced in the same way as that described in Example 1. Table 5 shows the optimum amounts of exposure in lux-second units to reproduce exactly the original images.

11 TABLE Optimum exposure Compound number: (lux-sec.) No sensitizer 8000 1 30 2 58 3 20 It is clear from Table 5 and FIGS. 8 to 10 that the novel sensitizers improve the photoconductivity and the spectrum characteristics of poly-3,6-dibromo-N-vinylcarbazole.

EXAMPLE 4 1 gram of brominated poly-N-vinylcarbazole (monobromo-substituted product), 0.5 gram of polycarbonate resin (commercially available as Panlite-C), 0.3 gram of chlorinated diphenyl (commercially available as Kanechlor) and 0.004 gram of a carbonium salt listed in Table 1 are dissolved in a mixed-solvent of 8 milliliters of ehlorobenzene and 2 milliliters of dichloroethane. This solution is applied to an aluminum plate or to a cellulose diacetate lm having a vacuum-evaporated lilm of cuprous iodide, by means of a blade coating and dried to form a layer of 12u in thickness. On these supports, electrophotographic images are produced in the same way as that described in Example 1. Table 6 shows the optimum amounts y of exposure in lux-second units to reproduce exactly the original images.

It is clear from Table 6 and FIGS. 1 to 4 that the novel sensitizers improve the photoconductivity and the spectrum characteristics of brominated poly-N-vmylcarbazole.

EXAMPLE 5 1 gram of brominated poly-N-vinylcarbazole (monobromo-substituted product), 0.3 gram of polycarbonate resin (commercially available as Panlite-C), 0.3 gram of chlorinated diphenyl (commercially available as Kanechlor), 0.0024 gram of phenyl (4-methoxypheny1)4'methoxynaphthyl(1)carbonium perchlorate (compound number 11), 0.0012 gram of bis(4methoxyphen yl)2'methoxynaphthyl(l)carbonium perchlorate (compound number 13) and 0.0024 gram of phenyl (4-methoxyphenyl)2 methoxynaphthyl(l)carbonium perchlorate (compound number 14), these three sensitizers are listed in Table 1, are dissolved in a mixed-solvent of 8 milliliters of chlorobenzene and 2 milliliters of dichloroethane. This solution is applied to an aluminum plate by means of a blade coating and dried to form a layer of 12p. in thickness. Electrophotographic images are produced in the same way as that described in Example 1. The optimum exposure to the said plate is 20 lux-seconds and the said photosensitive layer has a panchromatic photosensitive layer in the region of visible spectrum as shown in FIG. 11.

Furthermore, the said solution is applied to glassine paper by means of a whirler coating and dried to form a layer of 3p. in thickness. Electrophotogra-phic images are produced in the same way as that described in Example 1. The optimum exposure to the said paper is 60 lux-seconds.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as dened in the appended claims.

Having thus disclosed the invention, what is claimed is:

1. An electrophotographic material comprising a conductive support layer and a photoconductive insulating layer, the latter comprising a combination of weight parts of a photoconductive polymeric compound and 0.01 to 3.0 weight part of a sensitizer, said photoconductive polymeric compound comprising at least one compound selected from the group consisting of poly-N-vinylcarbazole, brominated poly-N-vinylcarbazole and polyacenaphthylene; said sensitizer comprising at least one compound selected from the group consisting of bis( 4methoxyphenyl)styrylcarbonium perchlorate,

tris 4-methoxyphenyl carbonium perchlorate,

bis (4-methoxyphenyl) naphthyl( 1') carbonium perchlorate,

tris( 4-methoxyphenyl)carbonium chloroferrate,

phenyl-4-ethoxynaphthyl l )carbonium perchlorate,

phenyl (3 ,4-dimethoxyphenyl) biphenyl (4' carbonium perchlorate,

phenyl( 4-methoxyphenyl -4-methoxynaphthyl( 1') carbonium perchlorate,

phenyl-bis (4-ethoxyphenyl)carbonium perchlorate,

bis (4-methoxyphenyl) -2-methoxynaphthyl( 1 carb onium perchlorate,

phenyl (4-methoxyphenyl) -2methoxynaphthyl( l' carbonium perchlorate,

bis (4-methoxyphenyl) phenanthryl (9 carbonium perchlorate,

phenyl 3,4-diethoxyphenyl) phenanthryl (9') carbonium perchlorate,

phenyl (ll-phenoxyphenyl) -4-methoxynaphthyl( 1') carbonium perchlorate,

bis(4methoxyphenyl) -4methoxystyrylcarbonium perchlorate,

bis(4-methoxypheny1) -w-phenylbutadienylcarbonium perchlorate,

bis (4-methoxyphenyl) -a- (4methoxypheny1) -4 methoxystyrylcarbonium perchlorate,

bis (4-methoxyphenyl -a- (4methoxyphenyl) -w-phenylbutadienylcarbonium perchlorate,

phenyl-bis(4-1nethoxyphenyl )carbonium perchlorate,

bis (ll-methoxyphenyl) 4phenoxyphenylcarboniurn perchlorate,

tris (4methoxyphenyl carbonium chlorozincate,

tris (4-methoxyphenyl) carbonium uoroborate and combinations thereof.

2. An electrophotographic material according to claim 1, wherein said combination is a combination of 100 Weight parts of Ibrominated poly-N-vinylcarbazole and 0.1 to 2.0 weight parts of said sensitizer.

3. An electrophotographic material according to claim 1, wherein said combination is a combination of 100 Weight parts of poly-3,6-dibromo-N-Vinylcarbazole and 0.1 to 2.0 weight parts of said sensitizer.

4. An electrophotographic material according to claim 1, wherein said combination is a combination of 100 weight parts of poly-N-vinylcarbazole and 0.1 to 2.0 Weight parts of `said sensitizer.

5. An electrophotographic material according to claim 1 wherein said combination is a combination of 100 weight parts of polyacenaphthylene and 0.1 to 2.0 weight parts of said sensitizer.

References Cited UNITED STATES PATENTS 3,037,861 6/1962 Hoegl et al. 96--l.5 3,240,597 3/1966 FOX 96--1.5 3,250,615 5/1966 Van Allan et al 96-1.7 3,274,000 9/ 1966 Noe et al. 96-1.5 3,279,918 10/1966 Cassiers et al. 96-1.5 3,418,116 12/1968 Inami et al. 96-1.5 3,421,891 1/1969 Inami et al. `961.6 3,464,819 9/ 1969 Inami et al. 9'6-15 OTHER REFERENCES Nelson, An Effect of the Anion on the Conductive Properties of Triphenyl Methane Dye Salts, J. Chem. Physics, vol. 20, pp. 1327, 1328, August 1952.

CHARLES E. VAN HORN, Primary Examiner U.S. Cl. X.R. 96-1.5 

